hotpath 0.15.0

Simple async Rust profiler with memory and data-flow insights - quickly find and debug performance bottlenecks.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135

#[cfg(test)]
pub mod tests {
    use hotpath::json::JsonThreadsList;
    use std::process::Command;
    use std::thread::sleep;
    use std::time::Duration;

    // HOTPATH_METRICS_PORT=6775 TEST_SLEEP_SECONDS=10 cargo run -p test-tokio-async --example basic --features hotpath
    #[test]
    fn test_threads_endpoint() {
        let mut child = Command::new("cargo")
            .args([
                "run",
                "-p",
                "test-tokio-async",
                "--example",
                "basic",
                "--features",
                "hotpath",
            ])
            .env("HOTPATH_METRICS_PORT", "6775")
            .env("TEST_SLEEP_SECONDS", "10")
            .spawn()
            .expect("Failed to spawn command");

        let mut json_text = String::new();
        let mut last_error = None;

        // Test /threads endpoint
        for _attempt in 0..30 {
            sleep(Duration::from_millis(1000));

            match ureq::get("http://localhost:6775/threads").call() {
                Ok(mut response) => {
                    json_text = response
                        .body_mut()
                        .read_to_string()
                        .expect("Failed to read response body");
                    last_error = None;
                    if json_text.contains("thread_count")
                        && !json_text.contains("\"thread_count\":0")
                    {
                        break;
                    }
                }
                Err(e) => {
                    last_error = Some(format!("Request error: {}", e));
                }
            }
        }

        if let Some(error) = last_error {
            let _ = child.kill();
            panic!("Failed after 30 retries: {}", error);
        }

        // Parse JSON response (server returns formatted values)
        let threads_response: JsonThreadsList =
            serde_json::from_str(&json_text).expect("Failed to parse threads JSON");

        // Assert we have at least some threads
        assert!(
            threads_response.thread_count > 0,
            "Expected at least 1 thread, got {}",
            threads_response.thread_count
        );

        assert_eq!(
            threads_response.thread_count,
            threads_response.data.len(),
            "thread_count should match data.len()"
        );

        let hp_threads: Vec<_> = threads_response
            .data
            .iter()
            .filter(|t| t.name.starts_with("hp-"))
            .collect();

        assert!(
            !hp_threads.is_empty(),
            "Expected at least one hp- thread, found none. Threads: {:?}",
            threads_response
                .data
                .iter()
                .map(|t| &t.name)
                .collect::<Vec<_>>()
        );

        for thread in &threads_response.data {
            assert!(thread.os_tid > 0, "Thread should have valid os_tid");
        }

        let _ = child.kill();
        let _ = child.wait();
    }

    // cargo run -p test-tokio-async --example guard_timeout_threads --features hotpath
    #[test]
    fn test_guard_timeout_output() {
        let output = Command::new("cargo")
            .args([
                "run",
                "-p",
                "test-tokio-async",
                "--example",
                "guard_timeout_threads",
                "--features",
                "hotpath",
            ])
            .output()
            .expect("Failed to execute command");

        assert!(
            output.status.success(),
            "Process did not exit successfully.\n\nstderr:\n{}",
            String::from_utf8_lossy(&output.stderr)
        );

        let stdout = String::from_utf8_lossy(&output.stdout);
        let expected_content = [
            "[hotpath]",
            "| threads",
            "Thread CPU and memory statistics.",
            "RSS:",
        ];

        for expected in expected_content {
            assert!(
                stdout.contains(expected),
                "Expected:\n{expected}\n\nGot:\n{stdout}",
            );
        }
    }
}